Genetically Modified Microorganisms in Steroid Biotransformation

In the last decade, research on steroid biotransformations catalyzed by recombinant microorganisms is marked by both tremendous scientific advances (reflected by a number of publications in high-ranking journals) and significant industrial interest. This broad interest is nourished by the large and still expanding steroid world-wide market and comes from both Biotech enterprises and large Pharma companies such as Roussel UCLAF, Sanofi-Aventis and Schering. Cytochrome P450-dependent steroid hydroxylation is at the very heart of this trend and for its application either whole cell systems or self-sufficient systems (that avoid NAD(P)H regeneration) are to be considered. As a general rule, whole cell approaches are more popular than (partly) isolated enzymes in biotechnological processes [50]. We will discuss the current state-of-the-art for the use of soluble and membrane-bound cytochromes P450 separately, as these two systems display fundamental differences with respect to their properties.

The relevant expression systems are limited to genetically engineered bacteria and yeasts. Although cells of insect or mammalian origin that recombinantly express cytochrome P450-dependent steroid hydroxylases are very valuable tools for the scientific investigation of the properties of these enzyme systems and for the screening of steroid hydroxylase inhibitors (e.g. [24, 51, 52]), in view of the tremendous expense of their cultivation conditions these systems cannot compete with microorganisms in the field of biotransformations at a technical scale. Recently, transgenic flowers have been developed in which the recombinant expression of cytochromes P450 results in the appearance of new and pretty colors (from light to deep purple) (cf. [53]). While these plants already have high selling rates, the corresponding P450s that contribute in such a nice way to the biotech-nological design of our environment are not steroid hydroxylases and will thus not be discussed here.

Heal Yourself With Qi Gong

Heal Yourself With Qi Gong

Qigong also spelled Ch'i Kung is a potent system of healing and energy medicine from China. It's the art and science of utilizing breathing methods, gentle movement, and meditation to clean, fortify, and circulate the life energy qi.

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